1. Field of the Invention
This invention relates to a method for controlling an optical disc player. Specifically, it relates to a method for controlling data accessing rate of the optical disc player.
2. Description of the Prior Art
The management and storage of documents is very important for a company or an individual. In the past, data was recorded on paper. Paper is inconvenient, especially for large amounts of data. Digital data stored generally in the storage media of a computer. A variety of storage media can be used to store the digital data of a user, such as an optical disc. Optical discs are cheap, small, and store large volumes of data. Therefore, it is convenient for users to store data by recording data on optical discs.
Besides text data and program data, the optical disc is generally used to store multimedia data, for example, audio stream or video stream, and an optical disc player is used to retrieve the data from the optical disc. FIG. 1 is a schematic diagram of an optical disc player system 10 according to the prior art. The optical disc player system 10 includes a micro-controller 11, a servo circuit 12, a motor driving circuit 14, a spindle motor 16, a track controlling circuit 18, a pick-up head 20, an optical disc 22, a non-volatile memory 24 stored a firmware, and a DRAM 26. The micro-controller 11 receives instructions inputted from a computer system to control operation of the optical disc player system 10, and manage operations of the motor driving circuit 14, the track controlling circuit 18, and the pick-up head 20 via the servo circuit 12. The micro-controller 11 also receives source data retrieved by the pick-up head 20, and feedback the digital data to a host 99 via the DRAM 26 as a buffer after decoding the source data. The motor driving circuit 14 controls the rotation speed of the spindle motor 16 to drive rotation of the optical disc 22. The track controlling circuit 18 controls the pick-up head 20 to retrieve the data from the track of the optical disc 22, that is the track controlling circuit 18 controls the pick-up head 20 to progress track seeking and track locking. In addition, the optical disc 22 is a kind of pure data disc, audio disc recording music, or video disc recoding image and music. Generally, the micro-controller 11 comprises a microprocessor for executing a firmware stored in the non-volatile memory 24. In some optical disc player system, the micro-controller 11 further comprises a digital data processor (or digital signal processor (DSP)) cooperated with the microprocessor to enhance the performance of the micro-controller 11. Therefore, the host 99 only sends high-level control commands to the micro-controller 11 of the optical disc player system 10, and the micro-controller 11 executes the corresponding firmware to control operation of the optical disc player system 10 according to the control commands. For instance, when the host 99 needs the data of the optical disc 22, only needs to send an instruction of data processing and assign the address of the data. The micro-controller 11 executes the corresponding firmware of the optical disc player system 10 to achieve the object of data retrieving of the host 99 through operations (such as to reach particular rotation speed of the spindle motor 16, moving and track locking of the pick-up head 20, and receiving the reflection of the laser from the optical disc 22) of the servo circuit 12, the spindle motor 16, the track controlling circuit 18, and the pick-up head 20.
FIG. 2 is a flow chart of the optical disc 22 retrieved by the optical disc player system 10 shown in FIG. 1. After power on, the micro-controller 11 initials and enters a main function 100; the optical disc player 10 is enabled at this time and is ready to retrieve the optical disc 22, comprising the steps of:
Step 102: receiving instructions inputted from the host 99.
Step 104: judging which type of the instructions received from the host 99; runs step 106 while the instructions are instructions of data processing; runs step 110 while the instructions are others instructions.
Step 106: controlling the motor driving circuit 14 via the servo circuit 12 to drive the spindle motor 16 and set a rotation speed.
Step 108: controlling the track controlling circuit 18 via the servo circuit 12 to drive the pick-up head 20 to retrieve data from a predetermined track; run step 102 while finish this step.
Step 110: executing corresponding action of the instructions; run step 102 while finish.
An application program will transmit the instructions of data accessing to the optical disc player 10 to retrieve data from the optical disc 22 when the user executes the application program and intend to get the data from the optical disc 22. For the video disc, the user utilizes the application program to extract data from the optical disc 22, for example, copy the data and store the data in a hard-disc player of the computer. When the micro-controller 11 of the optical disc player system 10 receives the instructions of data accessing transmitted by the application program, the micro-controller 11 executes the instructions of data accessing according to the firmware to control the motor driving circuit 14, the track controlling circuit 18 and the pick-up head 20. The motor driving circuit 14 drives the spindle motor 16 to set a rotation speed (ex. 10,000 rad/min), the track controlling circuit 18 drives the pick-up head 20 to operate the track seeking and track locking on this optical disc, the pick-up head 20 retrieves the data from the predetermined track of the optical disc 22 and feedbacks the data to the application program of the computer. Therefore, the application program stores the data retrieved from the optical disc 22 into the hard-disc player.
The spindle motor 16 drives corresponding spindle from a static status to a maximum speed supported by the optical disc player system 10 when the motor driving circuit 14 enables the spindle motor 16. For example, the maximum speed of the spindle of a 50× optical disc player tends to 10,000 radians per minute. However, the disc runout of the optical disc 22 will cause vibration and track locking of the pick-up head 20 under high speed rotation, that is easy to get error bits or the pick-up head 20 can not retrieve the data from the optical disc 22 smoothly. Therefore, the micro-controller 11 controls the spindle motor driving circuit 14 via a servo circuit 12 to slow the rotation speed of the spindle motor 16 down, for instance, from 10,000 radian/min to 8,000 radian/min. At this time, the pick-up header will retrieve the data of the optical disc 22 again. When the job of retrieving the data of the optical disc 22 is finished, the micro-controller 11 controls the spindle motor driving circuit 14 via a servo circuit 12 to recovery the rotation speed of the spindle motor 16 to 10,000 radian/min. In other words, the slowdown of the spindle makes a lower rotation speed of the optical disc 22 and a higher successful rate of retrieving data from the optical disc 22 for completing the operation of data accessing.
Considering the user utilizes the application program to play the video data of the optical disc 22, that is, the application program decodes the video data to play on the monitor and speakers equipped in a computer. First, the digital data of the optical disc 22 are read and stored in the computer for playing by media devices or application programs. The application program can also send commands instructions of data extraction (for example, read 10, read 12, read CD, or read CD MSF) to the optical disc player system 10 for data extraction. In the view of the optical disc player system 10, the procedure of data extraction is the same as the steps of copying video data and storing the data in a hard-disk drive. Generally speaking, the retrieving speed of extraction action is higher than the speed of playing action of the optical disc 22. Therefore, the optical disc player 10 has a DRAM 26 as a buffer for storing the data temporarily and the servo circuit 12 can provide the data stored in the buffer to the application program when the pick-up head 20 can't retrieve the data from the optical disc 22.
In one case of playing the video data of the optical disc 22, for some reason, such as low-quality optical disc and the serious vibration of the spindle motor 16, will cause transition of the spindle motor 16 between higher spindle speed and lower spindle speed. The transition results in more and more power consumption. Moreover, the micro-controller 11 wastes time to identify data and results in the image delay or some kind mosaic of the image on the screen.
Similarly, the transition also affects the operation of playing the audio data on the optical disc 22. For example, the user can utilize the application program to extract audio data from the optical disc 22 and store the audio file in the Hard-Disk Besides, and the user also can utilize the application program to play the audio data by retrieving the audio data from the optical disc 22, then the audio data can be transferred to the sound card connected to the optical disc player system 10, the audio digital data can be transferred to analog signal via DAC (Digital-to-analog converter), and the analog signal can be output via speaker connected to the sound card. As described above, the transition between higher spindle speed and lower spindle speed and transition time will cause the analog signal will be terminated temporarily and some kind intermittent sound outputted from the speaker.
In conclusion, the optical disc player system 10 of the prior art can't judge the action of instruction by the computer. Therefore, the optical disc player system 10 of the prior art still retrieves data (video/audio) from the optical disc 22 in the maximum spindle speed and the transition between higher spindle speed and lower spindle speed still results in low quality when playing a video disc or an audio disc.